Electron tube transmitter



Aug. 30,v 1932. R. B. MEYER ELECTRON TUBE TRANSMITTER Filed March 16,1927 Wam Patented Aug. 3o, 1932 ETEDQ S"I.",A'.T1=.'.`SY PAT ENT FEERAYMOND B. MEYER, F WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR, BY MESNEASSIGNMENTS, T0 WIRED RADIO, INC., 0F NEW' YORK, N. Y., A CORPORATIONOF' y DELAWARE ELECTRON TUBE TRANSMITTER Application led March 16, 1927.Seria1No. 175,757.

My inventionV relates broadly to. signal transmission systems and moreparticularly to a circuit arrangement foranelectron tube transmitterhaving its circuits supplied with power from an alternating currentsource.

e tems where power is obtained for exciting the electron tube circuitsfrom an alternating current'source with special means for preventingparasitic oscillations in the electron tube circuits.

Another object of my invention is to provide a balanced high frequencyoscillator, intermediate amplifier and'power amplifier circuit `1systemfor signal transmitters with means" for d'ephasing Aand cancellingcurrent components which would normally tend to establishA undesiredoscillations in the tube circuits for stabilizing the operation of thetransmitter. A Y

' My 'invention will be more fully understood fromthe specificationhereinafter following by reference to theacompanying drawing whichdiagrammatically illustrates an electron tube transmission circuitembodying the principles of my invention.

The transmission circuit involves a bi-lateral arrangement of sets oftubes connected as oscillators, frequency multipliers and highVfrequency amplifiers.A In the` drawing 1 12 is an inductance-in the135. plate circuit ofa set of tubes which may be considered as themaster oscillator circuit. G3` is a by-pass condenser by means of whichradio frequency energv'is applied to the grids oftubes 3 and( 4, whichmay be considered as theintermediate amplifier circuit. Theintermediatev amplifier circuit may be arranged to operate as afrequency doubler for increasing the frequency of the master oscillatorcircuit. C4 and C4 are radio frequency by-pass condensers in the platecircuits of the tubes in the intermediate amplifier. 14 is an inductancewhich may be tuned to the proper frequency by means of the vari ablecondenser B which isV shunted around the inductan ce. A2 is a radiofrequency ammeter used for deter-miningtheconditionvof resonance.v Itwill be noted that 14 has a connection at the center of the coil whichconnects to the laments ofthe vacuum tubes and that the connections fromthe plate by-pass condensers C4 and C4 are arranged 'symmetrically oneither side ofv the groundy or lament connection.

The gridsof the tubes 5 anl 6, which may be considered as the tubes inthe power amplifier circuit, are energized by means of taps taken offthe inductance 14 through the grid by-pass condensers C6 and CSC Againit will kbe noted that these taps are connected to the in'duct'ance 14symmetrically on either side kof the filament or ground point. C7 and C7are radio frequency by-pass condensers in the plate circuits of thevpower amplier tubes, and 6 by means of which energy is transferred tothe inductance 15.

The purpose of a balance is to neutralize the effect of couplingresulting from the interelement capacity in the vacuum tubes. Thebalance is obtained in the following manner. The radio frequency. energybeing transferred from the inductance 12 through the by-pass condenserC3 is employed to energize the grids of tubes 3 yand 4. It is desirableand necessary that this energy be confined to accomplishing thisfunction alone and that no appreciable amount of radio frequency be fedthrough the capacities between grid and plate which would have theeffect of coupling the intermediate amplifier circuit to the masteroscillatorcircuit which would result in reactions and other deleteriouseffects. Itis understood that tube 3 operates during one-half ofa cyclewhile tube 4 operates during the other half of Vthe cycle for amplifyingthe high frequency oscilla-tions supplied by the oscillator system. Theinter-element capacities in both tubes being approximately equal and theamount of inductance in the plate circuits of each tube beingapproximately equal and on opposite sides of the filament connection, itwill be seen that the radio frequency energy by-passed by the tubes willbey of approximately equal magnitude and 180 degrees out of phase sothat the magnetic fields set up in inductance 14 will cancel each other.resulting in no flow of current. Thus the effect of the inter-elementcapacit-ies and sir . vthe coupling resulting therefrom is neutral-yized. Therefore, no energy will befed over fromthe masterl oscillatorcircuit into the intermediate. amplifier circuit, nor will any 5vfeed-back take place between thesetwo cirl The'masteroscillator circuitis constituted 1 by electron tubes 1 and 2 connected in bal- Sancedrelationship for sustaining theoscilla- 10 tionsfof thepiezo electricYcrystal element 9.

connected in the common input circuit` of tubes 1 and 2 by means vof thecontactplates .10 and 11.

The balance between the intermediate ain- Y pliier and power amplifieris obtained in the energy used toenergize the grids of tubes 5' and6,being obtained fromY opposite sides of the filament 'connection on theinductance 14e yenergy `lay-passed by means ofthe inter-.elementcapacities in tubes 5 and'v6, the same beingof equal magnitude anddiametrically "opposite inI phase-,- cancel eachother to theiseliminated. v Y. f f The powerf'rsupply: system forv the transmittermaybe of any desired frequency. I

.Y have employed va source of alternating cur'- 'sof rent of a frequencyvarying between, -25 to f i 1,000 cycles.'k The pwerl supply line fromthe alternating' current source is brought in froml f terminals 19y andyafter p'assing'thrugh main switch 2O issuppliedtotheprimary windingsofthe several transformersl, 22 and 25. l

' circuitv breakerV 21 is interposed inv the pril.

mar-y circuit for thefprotection ofv thev system.

Atransformer 22 having secondarywinding transformer "'25 Vhavingsecondary winding 26and primary winding 27supplie'sthe platef circuitsfor the frequency multiplier tubesi" and 4 andthe `power ampliiier`tubes'and 6'. t-,Theprimary windings 24,27 and V1'? arevallL suppliedfrom the power source connected at vv19.Connections are provided at28-formeasf urements' ofthe'voltagefin yarious parts` of V otheffilament'circuits. Y .v

"g'f'AyresistanceRe is connected between the center ,or -r'nidy tapofthe secondary "winding 26;"of. transformerf25 and Vthe ley relay 29 from.whence the circuit proceeds tothe lila-'f VmentY or Vground .throughthe ammeter' A5.;

u When the contactsY of lth'ejke'y relay ,--29ffare closedthe platecircuits of the frequency mule Y tiplier and the"amplifier'tubesjd, 5`and@ Y arecompleted and plate current flows'.` 'This i the connectionsindicated bv 30 and Ael: -It' will'be notedfthatthe polarityofthev'potene yfollowing 'mannerfp The/radio frequency gis 180degrees outof-phase.'` Therefore, the'y 23and primary vwinding 24 suppliesthe'platey .potential for-.the oscillator tubes land 2. 1 The! resultsin avdrop of potential over'R'll. This'. resulting difference inpotential is* applied tothe gridsof the tubes 3 andll'by'means of'.

tial applied to the grids is.negativewithre-V specttothe iilamentsV yByproperly selecting the value ofRi the correct value of potential *Y maybe obtained for best operating characters` i y istics.

R3 is aresistanceY connectedV between the mid tap of secondarywindingeQfS of the plate transformer 22, Supplying the -potential yforthe master oscillator-tubes '1 and 2, andy filaments or ground. Thisarrangementproduces j the necessary negative vgrid potential. for. j'

y'ze i these 'tube'sf'ltv willV be noted that A`this Vciry cuit is notkeyed andthereinrethetubesif'arek permitted tooscillate continuously,va' feature that is necessary, or at least highlydesirable,

when quartzV crystalcont-rol is employed. The contacts of key relay29Vare controlled by winding '32 Lthrough a control linpeBB.V

LWhen the key contacts V*are closed,- the-fre--"-ify i quency multiplierand ampliier tubes 3,554,5*

and "6V receive..plate-current' andthe proper grid potentials` areautomaticallyestablished. y' 8.5 Now, as the ykeycontacts-29 arereleased the action issuch that resistance, in the formfofA I keycontact resistance is inserted in they lead e thatfconnectsthe center oftransformer seca d ondary- 26. to` ground or lila-ments; .Key 29.. whenopen effectsV the opening of circuit V226-:- 29-12. With this increasein resistance" the potential drop becomes greater resultingina greater'.negative potential being impressed uponjthew grids. This 'negativepotential or:

ratherf'the increase of resistance in tuinre.Vv l `duces the flowof-.plate currentandfbythe time, Y

thekey contacts29 :are `actually `open,.thej

nega-tive v potential on, the 'grids "has reached Y sucha:v magnitudethat thegrid'blocksland Y plate currentceases. topfl'owgiThis prevents larcing at thekey contacts and resultsfin efti- 1 vc'ientfa'nd cleancutleyaction.V `When the-.key

contacts are actually separatedthe resistance" .in the center' lead ispractically. infinite'andf the {negative,potentialV (static potential).Aiinpressed onthe grids equals in magnitude,the n voltage developed inthef-secondaryfof the; plate'transformer25 betweenthecenter tap of .noY' winding .26', and theeXtreme end.- The current that flows in thecenterjtapfisjuniedirecfV Y K. tional pulsatingcurrent and thus thegridsare never subjected to positive"fpotentials'-asjinf the case wheretransformers! are used tof. sup-'ang this 'systemis that as platecurrent tends to in-i f crease, the drop overV .the -resistance 219i@plyfwgrid potentials. 1 "Another advantage. of

creasesfwith resulting increase in the nega# tive Vpotential appliedtothegrids which Yin turn automatically regulates VV.the 1 plate;v cur?rent. y Hence it will'be seen., that therel isfestablished anautomatic.compensating action 'for'. Y limiting plate current toAdesiredValues.r

Alinerela'y 'Seis provided for the .controlY v A oftheloperation1 ofthetransformers through power switch indicated at 35S.N

.The arrangementof the electron tubes Y fbalanced Vcircuits in theloscillator, the interf mediateaamplilierk and the high' frequencyV,power-amplifier, systems is such that thetend?V n.

so y

ency of parasitic oscillations in the tube circuits interfering with thenormal operation of the system is substantially eliminated. The electrontube circuits connected to tubes 3 and l and to tubes 5 and 6 are soarranged that they operate to increase the amplitude of the signalingenergy without the transfer of inherent oscillatory currents in thedirection of the piezo electric crystal control element 9.- In this waythe oscillations developed in the circuits of tubes l and 2 undercontrol of the piezo electric. crystal element 9 are transfered andimpressed upon the power amplifier stages with minimum loss.

The balanced system of my invention has been found to be very practicalin operation and more efiicient than systems of single tube balancedcircuits heretofore employed in the art. The several circuits in thetransmitter, that is the oscillator, the frequency multiplier circuit,and the power .amplifier circuit, are all uniformly arranged in balancedrelationship and arranged to prevent reaction of one circuit uponanother.

While I have described my invention in certain preferred embodiments, Idesire that it be understood that modification may be made .and that nolimitations upon my invention are intended other than are imposed by thescope of the appended claims.

What I cla-im as new and desire to secure Y l by Letters Patent of theUnited States is as follows:

l. An electron tube transmitter constituted by a plurality of electrontubes connected in separate pairs, each of said tubes having grid,filament and plate circuits connected thereto, a power source ofalternating current for energizing the circuits of` said electron tubes,said pairs of electron tubes being connected in cooperative balancedrelationship for utilizing the eects of the alternating current powersource upon the circuits of said elect-ron tubes successively in `eachtube circuit of each pair of electron tubes, one pair of electron tubesbeing connected for the generation of high frequency oscillations andanother pair of electron tubes being connected for increasing theamplitude of the oscillations thus developed, and an electrostaticcoupling between the filaments of the rst mentioned pair of electrontubes and the said output circuits of succeeding pairs of electrontubes.

2. In a system for the transmission of high frequency radio signals thecombination of an oscillator comprising a pair of threeele ment electrontubes connected in cooperative balanced relationship and having a commonoutput circuit, an amplifier system the input Vcircuit of which iscoupled to said output circuit, said amplifier system also comprisingpaired three-element electron tubes connected in cooperative balancedrelationship, an alternating current source to excite the elements ofthe tubes in said oscillator and in said amplifier, and an inductanceacross the plate circuits of said amplifier tubes havingcondenser-coupled connections to the tube lilaments of said amplifiersystem whereby the radio frequency energy by-passed by the tubes iscaused to set up magnetic fields in said inductance which oppose andcancel one another by virtue of the approximate equality of theinter-element capacities in the tubes of the amplifier along with theoppositely phased excitation of the plates of said tubes in each pairwhile the grids thereof are parallel-connected and the filaments thereofare synchronously excited.

3. In a radio transmitting system the combination of a plurality ofstages for generation of oscillations and for amplification comprising aplurality of three-element electron tubes in bilaterally pairedarrangement with the grids of each pair parallel-connected, thefilaments of each pair parallel-connected and with capacitativelybridged output circuits for each stage, an alternating current sourcesupplying suitable potentials to each of the elements of said tubes andadapted to excite the plate elements thereof alternately as between thetubes of each pair, a tuning circuit in electrically balanced connectionwith the bridged output circuit for each stage, a load circuit connectedto the tuning circuit of the last stage and capacit-ative couplingsbetween each of said tuning circuits and the filament elements of thepreceding stage whereby reaction between successive stages is prevented.

RAYMOND B. MEYER.

IOC

